The Development of a Water-Free and Light Oil-Soluble Scale Squeeze Inhibitor Meeting Environmental Requirements

Abstract

The major technical drive for introducing oil-soluble scale inhibitors is to overcome the potential oil production decline caused by conventional aqueous-based scale-inhibitor squeeze packages in situations where relative permeability effects, water blocking, fluid lifting or deep penetration into the near well formation are of major concern. The particular requirement for a true oil-soluble scale inhibitor in a low-pressure reservoir with wells having lifting problems is that the package density needs to be lower than that of water. Additionally in certain geographical regions like Norway, the environmental regulations are very tight.This paper illustrates the development of a true oil-soluble scale-inhibitor package with zero water content. The product is light with a density of much less than 1 g/cm 3 and its environmental category in Norway is yellow. The successful product is the result of numerous formulation trials. Details of chemistry selection and the formulation development will be discussed in the paper. Following the success in formulation, the product has undergone stability, solubility and core flood testing to further evaluate its suitability as a squeeze inhibitor. The core flood results show an extended scale inhibitor return during the post flush; the scale inhibitor is still well above MIC (Minimal Inhibitor Concentration) for > 700 pore volume (PV) of post flush. The possible mechanism for this squeeze lifetime extension is discussed in the paper. No formation damage was observed during the reservoir condition multiphase core flood indicating the nondamaging nature of the true oil-soluble product. Based on this successful development, a field trial is planned.This paper discloses the development of a true oil-soluble scale-inhibitor formula that is water free, low density and in the yellow environmental category, which can be applied downhole as scale squeeze inhibitor providing a prolonged squeeze lifetime.